ZPE 1.7.8 focuses on a bunch of things but it's main focus is on the compiler.
ZPE 1.7.8 has new compiler optimisations that take a bit of strain from the interpreter and put more on the much faster compiler. These changes do not affect interpreted programs but affect ones compiled to a file such as the standard library. One of the first things that was changed is that compiler now removed assertions from a compiled program (these are only needed when the program is tested). Secondly, mathematical operations are now optimised so that operations that would come first are moved to the first place in the operation. Finally, inherited structures now are created at compile time rather than runtime.
I'm hoping to have 1.7.8 out by the end of the month, but it will all depend on how much other work I end up having to do as I'm quite a busy web dev at the moment.